Let me restate it... as presented somewhere in documentation on the web that Dr. Hsu designed the STF-1, and then redesigned it and that is currently being produced as the LFM-2 by outlaw, but I wouldn't be surprised if it's being made by HSU. Whether you choose to believe that or not isn't an issue to me, but it's an interesting statment true or not. If I were going to order either the Outlaw or the HSU I'd order the Outlaw and give it a comparo to my friends HSU. I suspect they'd be similar, they use the same overall enclosure (port relocated to bottom on outlaw), same plate amp and same driver.

Either way from what I've been told he has apparently designed subs for others in the past.

I know it is a fact that Hsu helped with the design of the Outlaw subs, there no questening that. I just thought it was an interesting statement that Hsu would say the Outlaw sub would be of a lower distortion design.

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Rick

"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud

Sean, I've been aware of the somewhat similar ACI filters, but I suggested the Harrison Labs items instead because they indicate a 12dB/octave slope rather than the 6dB/octave of the ACIs. This apparently means that they use a second-order filter with a series capacitor and a parallel inductor rather than only a series capacitor which forms a first-order 6dB/octave filter.

Have no personal experience with either one. You might take a look at the Harrison Labs site, especially page 2 of the catalog where it shows how the varying amplifier input impedance affects filter frequency. I'd noted that Carl's 320 has a 20Kohm input impedance, so the result should be essentially the same as the 22Kohm designed spec of 70Hz.

You might also take a look at page 3 to read a complimentary comment about it from Absolute Sound. Note however that some audio enthusiasts would probably(with a touch of paranoia)reject these filters out of hand because of the "cheap" capacitors and inductors used. I recall an incident from about three years ago when Ian participated more frequently when someone indicated to him that he'd been disturbed on seeing the caps and inductors in the Axiom crossover and had the affrontery to suggest that "quality" replacements be made. Ian of course politely replied that the components had been thoroughly tested to provide optimum performance and that no replacements were necessary.

A brief comment on the STF-1/LFM-2 comparison being discussed here: have no idea about "lower distortion", but as I've indicated previously, the LFM-2 has a greater rated bass extension, possibly because the different port location allowed using a slightly longer tuning tube. This would result in a lower extension, with slightly less maximum output higher up, which some might consider to be a reason to slightly prefer the LFM-2.

Thank you, John. From my limited understanding of slopes, I was under the impression that the steeper the slope the better--meaning the overlap of the sub and the speakers is kept to a minimum. The 6dB octave filter may seem too steep. I don't even know if my understanding is correct, though.

I'm going to have to read up on second-order filters.

These high-pass filters seemed such a simple thing at first. Who'd of thunk I'd actually have to LEARN something before buying!